Hand-held devices, particularly electric hand-held devices, are increasingly provided with capacitive sensors for detecting an approach of a hand to the hand-held device or a contact of the hand-held device by a hand. Providing additional interaction possibilities to operate a hand-held device constitutes the background of the approach or contact detection. Thereby, the usability of a hand-held device is to be enhanced or facilitated.
Arranging sensor electrodes of a capacitive sensor device on a sensor surface of a hand-held device is known from the state of the art. This sensor surface provides an interaction area, by which the hand-held device can receive the user inputs. The user inputs can be caused for example by the contact of the sensor surface and/or by an approach of a hand to the sensor surface. Under the sensor surface, a large-area emitter electrode (transmitting electrode) can be arranged, with which an alternating electric field can be stimulated. The signal detected by means of the sensor electrodes of the sensor surface or the data derived therefrom are related to the distance of an object, for example a finger, from the sensor electrodes.
However, it is a disadvantage that when the hand-held device is held in a hand, the position of a fingertip, for example the tip of the thumb, relative to the sensor surface can not be determined with the necessary accuracy when, for example, the thumb extends laterally into the sensor surface. For a multitude of applications though, a specific determination of the position of a fingertip relative to the sensor surface is a necessary prerequisite.
When a finger, for example a thumb of the hand that holds the hand-held device, moves within the sensor surface area, the alternating electric field surrounding the surface is distorted. However, with the same position of the tip of the thumb, the distortion of the alternating electric field depends on which side the thumb extends into the sensor surface. In order to take into account these different distortions of the alternating electric field of the sensor surface when determining the position of a fingertip, for example of a thumb, relative to the sensor surface, it is necessary to know in which hand the hand-held device is held. Therefore, for a correct determination of the position of a fingertip relative to the sensor surface, it must be additionally detected whether the hand-held device is held in the left hand or in the right hand.
In the state of the art, the hand position, that is, whether the hand-held device is held in the right hand or in the left hand, is not considered when detecting the position of a fingertip in relation to the sensor surface. For a multitude of applications it is not possible therefore to detect the position of the fingertip relative to the sensor surface with the necessary accuracy. In the state of the art it has been attempted to face this problem by predetermining the operation by means of the shape of the housing of the hand-held device. For example, the shape of the housing of a hand-held device can be designed in such a way that it can only be operated with the right hand or only with the left hand. The operation or the easiness of use of the hand-held device is thus considerably limited.